fix: correct tojson|safe usage in templates and update validator

- Remove |safe from |tojson in HTML attributes (x-data) - quotes must
  become " for browsers to parse correctly
- Update LANG-002 and LANG-003 architecture rules to document correct
  |tojson usage patterns:
  - HTML attributes: |tojson (no |safe)
  - Script blocks: |tojson|safe
- Fix validator to warn when |tojson|safe is used in x-data (breaks
  HTML attribute parsing)
- Improve code quality across services, APIs, and tests

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/api/v1/admin/companies.py

@@ -75,7 +75,7 @@ def create_company_with_owner(
         owner_username=owner_user.username,
         owner_email=owner_user.email,
         temporary_password=temp_password or "N/A (Existing user)",
-        login_url=f"http://localhost:8000/admin/login",
+        login_url="http://localhost:8000/admin/login",
     )